Gas lift valve



C. R. CANALIZO GAS LIFT VALVE Feb. 11, 1969 Filed Sept. 6, 1966 INVENTOR Carlos R. Conulizo 2 a;

Q/ ATTORNEYS Sheet Feb. 11, WGQ c. R. CANALIZO 3,426,786

GAS LIFT VALVE Filed Sept. 6, 1966 Fig.8

- INVENTOR Carlos R. Conulizo Fig.7 BY

W a ATTORNEY;

United States Patent 15 Claims ABSCT OF THE DISCLOSURE An annular gas lift valve having a central longitudinal flow passage, a lifting fluid pressure responsive valve, and a tubing or fluid pressure responsive valve, in series, for controlling admission of lifting fluid in the longidinal flow passage of the valve.

This invention relates to well tools and more particularly to air or gas lift valves for controlling the admission of gas or air into a column of fluid in a well to lift the column and to aid in flowing the fluid from the well.

It is one object of the invention to provide a new and improved well tool for admitting fluid into a flow conductor.

It is another object of the invention to provide a new and improved well tool for removing fluids produced by wells through an inner well tubing disposed in a well wherein gas from an annular flow passage between the wall of the well and the inner well tubing provides lifting power for transporting the well fluids to the surface through the inner wall tubing.

It is still another object of the invention to provide a well tool for the automatic removal of well fluids from a well bore including an intermittently opening value to permit gas or air flow from an annular flow passage within a well around an inner well tubing into the well tubing to aid in lifting well fluids present in the well tubing above the valve to the surface end of the well.

It is another object of the invention to provide a well tool for controlling fluid flow from an annular space in a well between the wall of the well and an inner tubing string positioned therein into the tubing string in response to combine forces provided by the pressure both within the inner tubing string and within such annular space when such combined forces exceed a predetermined value.

It is another object of the invention to provide a concentric type gas lift valve for inclusion in the inner tubing string of a well having a longitudinal central flow passage of a substantially uniform diameter and substantially equal in diameter to the internal bore of the tubing string in which the valve is included and having an outside diameter substantially equal to the outside diameter of collar connectors securing the gas lift valve in the tubing string.

It is another object of the invention to provide a gas lift valve which opens responsive to the fluid pressure within the tubing in which the valve is included and closes responsive to the pressure within a well around the tubing at the gas lift valve.

It is another object of the invention to provide a concentric type gas lift valve having means for readily varying its effective port size.

It is another object of the invention to provide a gas lift valve which includes a main or first annular sleeve type valve operable responsive to annulus pressure and a secondary or second annular valve arranged in series with the main valve and operable responsive to a differential between the fluid pressure within the tubing string and fluid pressure within an annular space around the gas lift valve.

It is another object of the invention to provide a gas lift valve having a secondary annular valve disposed in parallel flow relationship with a main annular valve and operable responsive to combined forces of both a spring and a fluid pressure differential applied across the secondary valve between the tubing string and an annular space around the gas lift valve.

It is another object of the invention to provide a gas lift valve having a secondary annular valve adjustable with respect to its opening and closing characteristics by an operating spring and by an adjusting ring which supports one end of and determines the initial compression of the spring.

Is is a further object of the invention to provide 'a secondary annular valve assembly in a gas lift valve including an annular spacer ring which permits increases in the diameter of the gas lift valve without corresponding increases in the effective areas of the secondary valve over which casing and tubing fluid pressures are applied thus minimizing corresponding increases in the requirements of the secondary valve operating spring.

It is still a further object of the invention to provide a gas lift valve including means for reducing its maximum flow rate through an annular orifice assembly to a level permitting continuous flow through the valve from the casing annulus into the tubing string to continuously lighten and produce well fluids as distinguished from intermittently producing them by introducing large spaced slugs of lift gas.

Additional objects and advantages of the invention will be readily apparent from the reading of the following description of a device constructed in accordance with the invention, and reference to the accompanying drawings thereof, wherein:

FIGURES 1 and l-A taken together constitute a longitudinal view in section and elevation of a gas lift valve embodying the invention, showing the valve in closed position;

FIGURE 2 is an enlarged view in section taken along the line 2-2 of FIGURE 1-A;

FIGURE 3 is an enlarged fragmentary view in perspective of a portion of the mandrel of the gas lift valve showing its orifice ring supporting structure;

FIGURE 4 is an enlarged fragmentary view in section of the secondary annular valve of the gas lift valve illustrated at its open position;

FIGURE 5 is an enlarged view in section along the line 55 of FIGURES 1-A and 4;

FIGURE 6 is an enlarged fragmentary longitudinal view in section and elevation of a portion of the secondary valve showing the orifice ring of FIGURE 7 assembled with the support structure illustrated in FIG- URE 3;

FIGURE 7 is an enlarged top view in elevation of the orifice ring of the form of the secondary valve shown in FIGURE 6; and

FIGURE 8 is an enlarged fragmentary longitudinal view in section of a modified form of secondary valve used with the gas lift valve of FIGURES 1 and 1-A.

Referring to the drawings, a gas lift valve 20 embodying the invention is connected into a well tubing string, not shown, by an upper coupling 21 and a lower coupling 22. The gas lift valve includes a tubular mandrel 23 provided with a substantially uniform longitudinal bore 24 defining a flow passage communicating at opposite ends with the tubing string when the gas lift valve is connected therein. The mandrel 23 is externally threaded along an upper end portion 23a and a lower end portion 23b to form the connection of the upper and lower couplings 21 and 22, respectively. A lower sleeve assembly 25 is disposed in concentric spaced relationship around the mandrel defining an annular flow passage 26 around the mandrel communicating with the exterior of the gas lift valve through ports 27 in the sleeve assembly and with the bore 24 through a plurality of circumferentially spaced inlet ports 31, FIGURE 1-A. Fluid flow in the flow passage 26 is controlled by a first main annular valve 32, FIGURE 1, and a secondary or second annular valve 33 disposed in series relationship in the fiow passage. AS is explained in detail below, the main valve is biased toward the closed position by dome gas pressure and opens responsive to the pressure of lift gas within a well bore around the gas lift valve. The secondary valve is operable responsive to tubing pressure and is biased toward open position by combined spring force and fluid pressure in the flow passage 26 and toward open position by the fluid pressure in a well bore around the gas lift valve.

The outside diameter of the mandrel 23 is reduced along a longitudinal section 23c defining the internal wall of an annular dome gas chamber 34 around the mandrel extending between an annular head member 35 and an annular base member 40 supporting an outer upper sleeve 41 in concentric space relationship around the mandrel defining the outside wall of the dome gas chamber 34. The head member 35 is suitably secured on the mandrel by annular weld 42 between the upper end surface of the head memher and the external surface of the mandrel. The head member is reduced in external diameter along a lower end portion 43 telescoped into the sleeve 41 and providing a downwardly facing external annular shoulder 44 which holds the sleeve 41 against upward movement. The inside surface of a portion of the head member is spaced from the outside surface of the mandrel section 23a defining an annular dome gas inlet passage 45. The head member is provided with an inlet port 50 closed by a plug 51 which is threaded into the port after the dome gas chamber has been charged with fluid to a desired pressure level. A spacer member 52, which may be a loosely coiled spring, is disposed within the chamber 34 between the head member 35 and the base member 40 to aid in supporting the sleeve 41 which may be formed of a relatively thin material and is subjected to pressures on opposite sides by the dome gas in the chamber 34 and the lift gas within a well bore around the outside of the gas lift valve.

The mandrel 23 is slightly enlarged along a section 23d received within the base member 40 and provided with one or more longitudinally extending external slots or recesses 53 which define longitudinal flow passages along the outside of the mandrel within the base member for communicating dome gas pressure from the chamber 34 into the main valve 32. The base member 40 is reduced in outside diameter along an upper end portion 40a telescoped into the sleeve 41 and providing an upwardly facing external annular shoulder 40b for holding the sleeve 41 against the downward movement. The base member 40 is also reduced in outside diameter along an intermediate portion 40c providing a downwardly facing external annular shoulder 40d and is further reduced in outside diameter along a lower end portion 40a.

The first or main valve 32 is an annular flexible sleeve formed of a material such as a reinforced rubber and is clamped along its upper end portion 32a between the reduced portion 40c of the base member 40 and an external intermediate sleeve 54 of the lower sleeve assembly 25 disposed in concentric spaced relation around the mandrel 23. The sleeve 54 is fitted along an upper end portion over the intermediate section 400 of the base member 40 and limited against upward movement over the base member by engagement of its upper end surface with the annular shoulder 40d of the base member. An O-ring seal 55 is disposed within an external recess in the intermediate base member portion 400 within the sleeve 54, The reduced lower end section 40e of the base member 40 has a plurality of external annular ridges 60 over which the upper end portion 32a of the main valve sleeve is clamped to hold the main valve sleeve against slippage from its clamped relationship between the base member and the sleeve.

The mandrel 23 is slightly reduced in outside diameter along a portion 23a which is provided with a plurality of external annular ridges 61 near its lower end over which a lower end portion 32b of the main valve sleeve is clamped by a compression sleeve 62 fitted over the mandrel and lower end portion of the main valve sleeve and crimped annularly around the valve sleeve end portion to securely hold the compressed sleeve against slippage on the mandrel and valve sleeve and to prevent fluid leakage from within the sleeve along the outside surface of the mandrel section 23d. The compression sleeve 62 is also clamped around upper and lower external longitudinally spaced flanges 63 and 64 formed on the mandrel 23. The flange 63 provides an upwardly facing external annular shoulder 65 engaged by the lower end surface of the main valve sleeve. An annular spacer sleeve similar to the compression sleeve is fitted within the compression sleeve 62 around the mandrel over the flanges 63 and 64 extending from the upper end of the flange 63 to the lower end of the flange 64.

Between its upper and lower end portions 32a and 3211, respectively, the main valve sleeve has a central valve portion 32c which is free to expand and contract radially on the mandrel within the sleeve 54 covering and uncovering the sleeve ports 27 responsive to the pressure around the sleeve as transmitted through the ports. The outside surface of the mandrel section 23d and the inside surface of the main valve sleeve portion 320 define an annular chamber portion 26a of the annular flow passage 26 around the mandrel within the main valve sleeve which communicates with the dome gas chamber 34 through the longitudinal flow passages 53 so that dome gas within the dome gas chamber is transmitted into the chamber portion 26a behind the main gas sleeve biasing its central portion 32c radially outwardly toward the inside wall surface of the sleeve 54 over the ports 27. The sleeve 54 is reduced in internal diameter along a central portion 54a which is provided with internal longitudinally extending circumferentially spaced slots 54b through which lift gas flows downwardly from the ports 27 around the main valve sleeve portion 32c when it is contracted inwardly.

A sleeve type annular resilient check valve 72 is clamped around the mandrel 23 below the flange 64 around an upper end portion by the lower end portion of the compression sleeve 62 to prevent upward flow into the flow passage 54b from within the annular flow passage 26 below the check valve. The mandrel is provided with external annular ridge portions 73 below the flange 64 over which the check valve is clamped to aid in holding on the mandrel. The lower resilient free end portion 72b of the check valve expands and contracts radially within the annular flow passage 26 so that when the main sleeve valve 32 is at open position fluid flows into the sleeve 54 through its ports 27, downwardly around the sleeve valve into the slots 54b into the annular flow passage 26 around the check valve portion 72b. When a pressure differential is applied across the resilient portion of the check valve within the flow passage 26 from below the check valve, the check valve is biased radially outwardly, FIGURE l-A, against the inside surface of the sleeve 54 thereby preventing upward flow within the flow passage 26 into the longitudinal slots 54b.

The lower end portion of the sleeve 54 is telescopically fitted over a reduced upper end portion of a sleeve support and valve guide ring member 75 having a pilot valve inner guide tube portion-75a extending downwardly. The lower end surface of the tube 54 is suitably secured, as by an annular weld 80, to the ring member 75. The inside surface of the ring member 75 is concentrically spaced around the mandrel 23 defining a portion of the annular govlv passage 26 through the ring member around the man- The mandrel 23 is provided with an external annular centralizing and flow restricting flange 82 located within the ring member 75, FIGURES 1-A and 3, and having an outside diameter substantially equal to the inside diameter of the ring member 75 so that the flange serves as a centralizing member to hold the ring member at its concentric spaced relation and position around the mandrel. The flange 82 additionally functions to support a split orifice ring 83, FIGURES 6 and 7, to restrict flow through the gas lift valve. As shown in FIGURE 3, the flange 82 has a plurality of circumferentially spaced flat surface portions 84 each of which lies in a plane extending tangent to the outer surfacee of the mandrel 23. The flat flange surface portions 84 are circumferentially spaced providing a plurality of circumferentially spaced cylindrical surface portions 85 which engage the internal surface of the ring member 75 holding the ring member concentrically spaced or centered on the mandrel. The flange 82 includes an external annular slot 90 which receives the orifice ring 83. The flat flange surfaces 84 in combination with the inside surface of the ring member 75 define a plurality of circumferentially spaced flow passages through which fluid flows in the annular flow passage 26 around the flange 82.

In intermittent flow use, where alternate large lift gas slugs are injected into the well fluids, the gas lift valve functions with the flange 82 as in FIGURES 1-A and 3 without the orifice restriction ring 83. If, however, flow restriction is desired as in continuous injection of lift gas, the split ring 83 is positioned in its recess 90 of the flange. The orifice ring has a plurality of external circumferentially spaced slots 91 through which fluid flows around the ring within the ring member 75. The number of slots 91 equals the number of the flat surface portions 84 on the supporting flange so that the orifice ring may be disposed in the annular slot of the flange with each of the slots 91 being aligned with a surface portion 84. Fluid then flows past the flange through the ring slots 91 at a lower rate of flow than when the orifice ring is not used.

Such restricted flow is preferred when lift gas is injected on a continuous basis for aerating the well fluids.

The second or secondary valve 33 is an annular valve member slidably positioned concentrically between the lower end portion 75a of the ring member 75 and lower sleeve 92 of the sleeve assembly 25. The sleeve 92 is supported in spaced concentric relationship on the mandrel from a retainer ring 93 held on the mandrel by a nut 94 threaded on the lower end section 23b of the mandrel. A downwardly facing external annular flange surface 95 on the ring member 75 limits the sleeve 92 against upward movement. The retainer ring 93 is suitably secured as by an annular weld 93a with the lower end of the sleeve 92. A pair of O-rings 93b disposed in external annular recesses in the mandrel 23 seal around the mandrel within the ring 93. The nut 94 is held against rotation of the mandrel by a set screw 94a threaded through the nut against the threaded outer surface of the mandrel. A plastic ball, not shown, may be positioned between the inward end of the set screw 94a and the threaded surface of the mandrel to minimize damage to the mandrel threads by the set screw.

The secondary valve is reduced in internal diameter along a lower end portion 33b providing an upwardly facing internal annular shoulder 33c engageable with the lower end surface of the ring member portion 75a limiting the upward movement of said secondary valve. An O-ring 101 supported in an external annular recess of the ring member portion 75a seals around the ring member within the secondary valve while a seal is effected around said valve within the sleeve 92 by an O-ring 102 disposed in an external annular recess of secondary valve. A slotted secondary valve operator sleeve 103 is telescopically secured along an upper end ring portion 103a over a lower end portion of the secondary valve. The operator sleeve has a plurality of longitudinal ribs 1030 interconnecting its upper end lower ring portion defining circumferentially spaced longitudinal slots 103d for fluid flow in the flow passage 26 along the operator sleeve. The operator sleeve 103 is biased upwardly by a spring 104 disposed between the sleeve 92 and mandrel 93. The upper end of the spring engages a lower ring portion 103!) of the operator sleeve. The lower end of the spring 104 is supported on a spacer ring 105 which is held against downward movement by a lock ring having a plurality of circumferentially spaced set screws 111 the inner ends of which rest on an external annular flange 112 on the mandrel 23 holding the adjusting ring against downward movement on the mandrel. The height of the spacer ring 105 determines the extent the spring 104 is constantly compressed and then the force of the spring on the operator sleeve is variable by changing spacer rings.

A secondary valve seat assembly 113 is supported in annular concentric relationship on the mandrel below and for engagement by the secondary valve. The seat assembly is supported on an enlarged portion 23e of the mandrel 23 which provides an upper external annular upwardly and inwardly convergent shoulder surface 114 around the mandrel which normally is not engaged by the internal annular downwardly divergent seat surface 330 of the secondary valve but may serve as a secondary seat surface in the event of deterioration or failure of the seat assembly 113. The seat assembly comprises a resilient annular seat member 114 supported in an annular retainer 115. The seat member is disposed within an internal upwardly opening annular recess 115a of the retainer. The seat member extends above the retainer and is provided with an external annular downwardly and outwardly divergent seat surface 114a engaged by the seat surface 330 on the secondary valve when the secondary valve is at its lower closed portion, FIGURE 1-A. The seat assembly is secured on the mandrel by a plurality of circumferentially spaced arcuate crimped portions 115b, see particularly FIGURE 5, which are received wit-bin an external annular recess in the enlarged portion 23@ of the mandrel. The circumferentially spaced crimped portions of the seat assembly support ring are formed only along a lower end portion of the ring. An O-ring 121 disposed in an external annular recess 122 of the mandrel 23 within the retainer ring 115 seals between the mandrel and support ring below the seat member 114. The rib portions 1030 of the pilot valve operator sleeve 103 are reduced in wall thickness along their upper end portions as best seen in FIGURE 4 so that the operator sleeve freely slides over the seat assembly 113. The secondary valve is supported on the upper operator sleeve ring portion 10319 with the ring portion being received in a downwardly and outwardly facing external lower end recess 33d of the secondary valve. The longitudinal slots 103d allow fluid flow along the flow passage 26 past the valve seat assembly to the ports 31 so that fluid transmitted from above the secondary valve when it is at its open position, FIGURE 4, flows downwardly along the mandrel into the ports 31.

The gas lift valve 20 is incorporated into a conventional gas lift system comprising well equipment which usually includes a string of relatively small pipe referred to as tubing disposed within a large diameter pipe called casing. Generally a packer is installed within the well casing around the tubing string below the gas lift valves defining the lower end of the casing annulus into which the lift gas is injected as illustrated at p. 3773 of the Composite Catalog of Oil Field Equipment and Services, 1966-67 edition, published by World Oil, Houston, Tex. Several of the gas lift valves are included along the length of the tubing string at different depths, each valve comprising a short section of the tubing. The well installation may include a conventional intermitting device, not shown, which controls the admission of lift gas into the well casing by allowing the lift gas to be injected into the casing annulus around the tubing string at relatively great rates for short periods of time at regularly spaced intervals of time. The lift gas may, on the other hand, be supplied to the casing annulus at a constant rate through a choke, not shown, which limits the flow rate into the annulus to a value below the rate at which the lift gas flows from the annulus into the tubing string through the gas lift valve admitting the gas into the tubing string. Well fluids are produced from the well through the tubing string by the lift gas which is subsequently injected from the annulus into the tubing through one of the gas lift valves.

Prior to installing each valve its operating conditions are established to the extent the structure of the valve permits. The opening and closing characteristics of the second or secondary valve are determined by the choice of the spring 104 and by the selection of its spacer 105 which adjusts the initial compression of the spring. The dome gas chamber 34 is charged with gas through its port 50 until the desired pressure is established within the chamber. The dome gas chamber is then sealed by securing the threaded plug 51 in its port 50, FIGURE 1.

When the gas lift valves are assembled in a tubing string and before the tubing string is inserted into a well the secondary valve 33 of each valve is at its open position, FIGURE 4, while the main valve sleeve 32 of each gas lift valve is expanded to its closed position over the ports 71, FIGURE 1. The secondary valve is biased upwardly toward its open position by the force of the spring 104 against the lower end surface of the lower ring portion 103:: of the operator sleeve 103 and by the upward force from fluid pressure within the annular flow passage 26 of the gas lift valve over an effective annular area defined between the line of sealing engagement of the O-ring 101 with the inside wall surface of the portion 33a of the secondary valve and the line of sealing engagement of the O-ring 102 with the inside wall surface of the sleeve 92. The secondary valve is biased downwardly toward its closed position by the force of fluid pressure communicated through the sleeve ports 100 to the valve over the same effective annular area defined, as stated above, by the O-rings 101 and 102. When each gas lift valve is in the atmosphere before insertion into a well, the fluid pressure applied to each secondary valve through both the ports 31 and the ports 100 is atmospheric. The upward and downward fluid pressure on the secondary valve thus counterbalance each other and the net upward force on the secondary valve is provided by the spring 104 which biases said secondary valve toward and holds it at its open position, FIGURE 4.

Generally, the gas lift valves are installed in a well which has been rendered inoperative by substantially filling the well with a liquid, such as a conventional drilling fluid, to prevent fluid flow from the well during installation of the gas lift system. As the tubing string including the gas lift valves is lowered into the liquid filled well bore, the liquid rises within the tubing string and thus is present both in the annular space around the tubing string and within the longitudinal bore of the tubing string so that the equal hydrostatic pressures are applied to the secondary valve of each gas lift valve through both the annulus ports 100 and the ports 31 of each valve. A net upward force on each secondary valve is therefore provided by its spring 104 so that each secondary valve remains at its open position with the gas lift valve immersed in the liquid in the well bore. The main valve sleeve of each gas lift valve, however, is at its closed position over the ports 71 in the atmosphere and remains expanded to such position until the valve is lowered to such a depth within the liquid filling the well that the hydrostatic pressure of the liquid exceeds the dome gas pressure to collapse the valve sleeve sufiiciently to displace it inwardly from the ports 71. Since the dome gas pressure of each gas lift valve is established at a value suflicient to hold the valve at its closed position until lift gas pressure around the valve is at a desired level for injection into the tubing string, it is thus necessary that the dome gas pressure be at substantial value, which generally exceeds the combined atmospheric pressure and hydrostatic pressure of the liquid within a well bore until the valve is at an appreciable depth.

When a tubing string containing the gas lift valves is at the desired depth and secured within a liquid filled well bore, the gas lift valves generally are all open (both the secondary and main valves) for the reasons stated above. To bring the well into production, the liquid in the well bore is removed by conventional procedures which generally involve the displacement of the liquid to the surface through the tubing string by injecting gas under pressure into the casing annulus. The liquid is displaced downwardly in the annulus through the gas lift valves into the tubing string, and through the tubing string to the surface end of the well. The liquid level is so lowered to a depth known as its working level after which the first gas lift valve in the tubing string above the surface of the liquid functions as the operating gas lift valve serving to inject gas from the well bore annulus into the tubing string. Generally the gas lift valves below the working level of the well liquids are open due to the added hydrostatic pressure of the liquid which provides force in excess of the force of the lift gas pressure. The gas lift valves above the functioning valve are, if any, however, are adjusted to remain closed after the well liquids are lowered to their working level. The functioning gas lift valve so serves until the liquid in the well is lowered to a level below the next lower gas lift valve in the tubing string.

The main valve sleeve 32 and the secondary valve 33 of the gas lift valve 20 must both be at their open positions for fluid communication between the casing annulus and the tubing string through the gas lift valve. The main valve sleeve is exposed to and operable responsive to the casing annulus pressure. The secondary valve is operable responsive to the differential between the fluid pressures in the gas lift valve bore 24 and in the casing annulus around the gas lift valve and is adjusted to function responsive to the height of the column of well liquids within the tubing string above the operating gas lift valve. Thus, with the liquid in the well bore at its working level the pressure of the lift gas in the casing annulus around the tubing string is raised to the value required for injection through the gas lift valve into the tubing string. At such value the pressure of the lift gas in the casing annulus transmitted through the ports 71 against the outer surface of the main valve sleeve 32 is greater than the force resulting from the pressure of the dome gas in the chamber 34 against the inside surface of the main valve sleeve. The main valve sleeve is collapsed radially inwardly away from the ports 71 to permit fluid communication through the ports into the outer sleeve 54. The lift gas pressure is transmitted downwardly within the sleeve 54 through its longitudinal internal grooves 54b around the main valve sleeve past the check valve 72 which is biased inwardly away from the inner surface of the sleeve 54. The increased pressure is transmitted downwardly to the line of sealing engagement between the secondary valve and its seat member 114. At this stage in the operation of the gas lift system the secondary valve of the operating gas lift valve is closed since the downward force of the pressure of the lift gas in the annulus as applied to the secondary valve through the ports over the previously described effective annular area defined by the O-rings 101 and 102 is greater than the upward force of both the spring 104 and the fluid pressure in the tubing string transmitted through the mandrel ports 31 on the secondary valve over an annular area defined between the line of sealing engagement between the seat surfaces 33c on the secondary valve and 114a of the secondary valve seat assembly and the line of sealing engagement of the outer O-ring 102 with the inside surface of the sleeve 92.

With the main valve sleeve open and the secondary valve closed, the liquid level of the well fluids in the tubing string rises responsive to formation pressures until the liquid is at a predetermined level at which gas injection is desired. At such level the hydrostatic pressure of the liquid within the tubing string applies an upward force on the secondary valve over the annular area defined by the lines of sealing engagement of the seat surface of the secondary valve with the secondary valve seat assembly and between the outer O-ring 102 with the inside surface of the sleeve 92. This fluid pressure force on the secondary valve together with the force of the spring 104, exceeds the downward force resulting from the pressure of the lift gas in the annulus acting on the secondary valve. The secondary valve is moved upwardly to its open position, FIGURE 4, permitting the lift gas to flow downwardly in the annular passage 26 past the previously opened main valve sleeve, between the secondary valve seat 330 and its seat assembly surface 114a, through the longitudinal slots 10341 in the secondary valve operator sleeve 103 between the mandrel 23 and the sleeve 92 and into the injection ports 31 of the mandrel. The lift gas flowing into the bore 24 of the gas lift valve enters the column of well fluids in the tubing string displacing the column toward the surface end of the well. The rate of flow of the lift gas into the tubing string through the gas lift valve is greater than the rate of supply of the lift gas to the casing annulus so that as the lift gas flows through the gas lift valve into the tubing string the casing annulus pressure is reduced. The main sleeve valve 32 remains open permitting flow of the lift gas into the tubing string until the casing annulus pressure is reduced to a value below the pressure to which the dome chamber 34 is charged at which time the force of the dome gas pressure within the main valve sleeve expands the valve sleeve into closed relationship over the ports 71. The gas lift valve is de signed so that by the time the casing annulus pressure is reduced to the level at which the main valve sleeve expands to closed position enough lift gas has been introduced into the tubing string to displace the column of liquids above the gas lift valve in the tubing string to the surface.

While the lift gas is flowing from the casing annulus into the tubing string through the gas lift valve, the secondary valve is in its open position subjected to the downward force of the casing annulus pressure through the ports 100 acting in a downward direction on the previously defined effective annular area defined by the O-rings 101 and 102 while said valve also is subjected to a substantially equal upward force resulting from the pressure of the lift gas flowing downwardly in the annular passage 26 which is acting upwardly over the same annular area between the O-rings 101 and 102. While the fluid pressures both upwardly and downwardly on the secondary valve are substantially equal, a net upward force is applied to said valve by the spring 104, thereby maintaining it at the open position of FIGURE 4. After closure of the main valve sleeve as a result of the reduced casing annulus pressure, the pressure within the gas lift valve below its check valve 72 is the pressure within the tubing string at the gas lift valve which, at the moment of closure of the main valve sleeve, is substantially the same as the casing annulus pressure around the valve. However, after the closure of the main valve sleeve and as the fluids within the tubing string are displaced or unloaded by the lift gas from the tubing string at the surface end of the well, the hydrostatic pressure within the tubing string at the gas lift valve progressively decreases. This decreasing pressure within the tubing string is transmitted through the ports 31 upwardly within the annular flow passage 26 thereby applying a reducing upward force to the secondary valve over the annular area defined by the O-rings 101 and 102, as previously discussed. When this upward force from the tubing pressure combined with the upward force of the compressed spring 104 decreases to a value below the downward force on the secondary valve resulting from the casing annulus pressure transmitted through the ports 100, the secondary valve is moved back down- 10 wardly to its closed position as illustrated in FIG- URE 1A.

The main valve sleeve 32 remains expanded by the force of the dome gas pressure to its closed position over the ports 71 so long as the casing annulus pressure remains below the pressure of the dome gas. Similarly, the secondary valve remains at its lower closed position until the pressure of the fluids in the tubing string again rises to a value suflicient with the force of the spring 104 to move the secondary valve upwardly to its closed position.

When the casing annulus pressure again increases to a value in excess of the pressure of the dome gas in the chamber 34, the main valve sleeve 32 is collapsed inwardly to its open position with the pressure of the lift gas in the casing annulus again being transmitted downwardly through the annular passage 26 to the line of sealing engagement between the closed secondary valve and its seat member 114-. The main valve sleeve remains open with the secondary valve closed until the pressure of the well fluids in the tubing string again rises to a level sufficient in combination with the force applied by the spring 104 to the operator sleeve 103 to lift the secondary valve to its open position against the force of the annulus pressure applied to the secondary valve through the ports 100'. When the tubing pressure so arises, the secondary valve again opens to repeat the above described cycle of introducing lift gas into the tubing string to displace the well fluids above the gas lift valve to the surface subsequent to which the cycle continues with the main and secondary valves again closing until the casing annulus and tubing pressures increase sufficiently to repeat the cycle.

Generally, the main valve sleeve opens prior to the opening of the secondary valve since the casing annulus pressure normally recovers to its operating value before the liquid level in the tubing string rises to the height necessary to open the secondary valve. However, if the liquid level in the tubing string rises sufficiently to open the secondary valve prior to the opening of the main valve sleeve, the tubing pressure is transmitted upwardly past the secondary valve to the check valve 72 whose lower end portion 72b is biased outwardly by the tubing pressure against the inside surface of the sleeve 54 preventing the pressure being transmitted to the main valve sleeve. The check valve 72 serves the further function of preventing back flow from the tubing string into the casing an nulus through those open gas lift valves located below the liquid level in the casing annulus. Such valves generally are at their open positions since the hydrostatic pressure of the liquid in the casing annulus in combination with the pressure of the lift gas on the surface of the liquid usually exceed the dome gas pressure of each of the valves so that the main valve sleeve of each such valve is forced to its open position, while, similarly, the hydrostatic pressure of the liquid within the tubing string is sufficient when combined with the force of the compressed spring 104 to hold each secondary valve at its open position. Once the main and secondary valves of the gas lift valves below the liquid level are open, there is pressure equalization in the annular flow passage 26 across the secondary valve of each of such gas lift valve, as discussed previously, so that the secondary valve is held at its upper open position by the force of the compressed spring 104. The check valve 72 in each of the gas lift valves, of course, prevents back flow in each of the valves from the tubing string into the casing annulus.

The orifice restriction ring 83 is assembled on the support flange 82 in its recess when it is desired that lift gas flow through the gas lift valve from the casing annulus into the tubing string at a lower rate. Such reduced lift gas injection rate is employed when continuous production by constant lightening of the well liquids column as distinguished from intermittent flow is desired, as discussed above. When so producing a well, the lift gas enters the well fluids in a constant stream rather than in large intermittent spaced slugs of gas. Under such conditions the main and secondary valves are adjusted to remain open under predetermined constant conditions.

FIGURE 8 illustrates an alternate form of secondary valve used where it is desired to reduce the relative effective cross sectional area of the secondary valve exposed both to the casing annulus pressure and the tubing pressure. Stated otherwise, the form of FIGURE 8 is used so that the diameter of a gas lift valve may be increased without increasing the area of its secondary valve exposed to tubing and casing annulus pressures. In FIGURE 8, those valve components which are identical to components previously described and illustrated are referred to by the same reference numerals while similar modified components fulfilling the same functions as those previously described and illustrated are referred to by the same reference numerals used in FIGURES 1 through 7 with a prime mark added. The second or secondary valve 33 is supported on the control sleeve 103 by its upper ring portion 103a which is received in the downwardly and outwardly opening recess 33d of said secondary valve. The secondary valve is limited against the downward movement at its lower closed position by engagement of its seat surface 330' with the upper outer corner edge 114b of the annular resilient seat member 114' which is disposed within an upwardly opening annular recess 115a in the ring member 115 of the secondary valve seat assembly 113-. The valve seat assembly is held on the mandrel 23 by its crimped portions 115b received within the external recess 120 of the mandrel. An O-ring 121 disposed in an external annular recess 121a of the mandrel within the ring member 115' seals between the ring member and the outside surface of the mandrel to prevent leakage along the mandrel within the seat assembly when the secondary valve is at its closed position as shown in FIGURE 8. The upper tubular portion 33a of the secondary valve is slideably received between the ring guide member 75 between its lower end portion 75a and a concentrically positioned spacer ring shaped spacer 130 supported within an upper reduced thickness end portion 92a of the sleeve 92'. The O-ring 102 disposed in an external annular recess 102' of the lower end portion 75a. of the ring member 75 seals between the ring member and the upper tubular portion of the secondary valve. An O-ring 131 disposed in an internal annular recess 131' of the spacer 130 seals within the spacer around the upper cylindrical portion 331:. of the secondary valve. A seal is effected within the sleeve 92' around the spacer 130 by an O-ring 132 disposed in an external annular recess 132 around the spacer ring. An upper end portion of the spacer ring 130 is slotted providing circum'ferentially spaced ports 100' to communicate the secondary valve above the O-rings 102 and 131 with the casing annulus through an annular space 135 between the ring member 75 and the spacer 130. The modified form of secondary valve functions in exactly the same manner responsive to the same forces as the secondary valve 33 previously described and illustrated. The secondary valve 33 is biased downwardly by a force resulting from the casing annulus pressure transmitted through the ports 100 and downwardly in the annular space 135 over effective area of said secondary valve defined by the line of sealing engagement of the O-ring 102 with the inside surface of the portion 33a of said valve, and the line of sealing engagement of the O-ring 131 with the outside surface of the portion 33a of said valve. The secondary valve is biased upwardly by the force of the compressed spring 104 acting against the lower end surface of the operator sleeve 103 in combination with the fluid pressure in the annular flow passage 26 applied in an upwardly direction to said valve over the same effective area of the valve defined between the O-rings 102 and 131. The secondary valve 33' opens and closes under the same conditions as the secondary valve 33 previously discussed.

The alternate form of second or secondary valve in FIGURE 8 is useful where the gas lift valve is increased in diameter to the extent that the space available for the spring 104 is not adequate to accommodate a spring capable of applying the required upward force to said secondary valve. As the diameter of the gas lift valve is increased in the alternate form of FIGURE 8, the wall thickness of the support ring portion a and the spacer ring are increased thereby minimizing the increase of the wall thickness of the secondary valve portion 33a and then minimizing the increase in the pressure responsive areas of the valve. Consequently such valve diameter increase do not require corresponding increases in the strength of a spring 104 to open the secondary valve. Therefore, when in making larger gas lift valves the practical limits of spring design consistent with the space available for the spring 104 is exceeded, the embodiment of FIGURE 8 is utilized to minimize the spring requirements. By insertion of the spacer 130 the relative effective annular sealed area of the secondary valve defined by the O-rings 102 and 131 is reduced as compared with the design of FIGURE 4 so that as the gas lift valve increases in diameter the force applied to the secondary valve by the lift gas in the casing annulus may be held within practical limits as dictated by the springs 104 which may be placed in the available space.

It will now be seen that a new and improved well tool for admitting fluids into a flow conductor has been described and illustrated.

It will also be seen that a new and improved well tool has been described and illustrated for removing fluids produced by wells through an inner tubing disposed in a well wherein a gas from an annular flow passage between the inner well tubing and the wall of the well provides lifting power for transporting well fluids through the well tubing to the surface.

It will be further seen that the well tool provides for the automatic removal of well fluids from a well bore and includes an intermittently opening valve to permit gas or air from an annular flow passage within a well around an inner well tubing to flow into the well tubing to aid in lifting well fluids present in the well tubing above the valve to the surface.

It will also be seen that the well tool is operable to permit fluid flow from an annular space in a well around an inner well tubing into a well tubing responsive to forces provided by fluid pressure both within the inner well tubing and within the annular space around the well tubing.

It will be further seen that a new and improved concentric type gas lift valve has been described and illustrated.

It will also be seen that the gas lift valve is included in the inner tubing string of a well and has a longitudinal central flow passage substantially equal to the diameter of the bore through the well tubing and an outside diameter substantially equal to the outside diameter of couplings employed to connect the gas lift valve into the well tubing.

It will be further seen that the gas lift valve opens responsive to fluid pressure within the tubing string in which the valve is included and closes responsive to annulus pressure within a well around the tubing string.

It will also be seen that the gas lift valve includes a main or first annular sleeve type valve operable responsive to the annulus pressure and a secondary or secondary annular valve arranged in series with the main valve and operable responsive to the fluid pressure differential between the pressure within the tubing string in which the gas lift valve is included and the pressure around the gas lift valve.

It will also be seen that the gas lift valve includes a secondary valve disposed in series flow relationship with the main valve of the gas lift valve and operable responsive to the forces of both a spring and a fluid pressure differential applied across such valve between the tubing string and the casing annulus.

It will be further seen that the secondary valve of the gas lift valve is adjustable with respect to its opening and 13 closing characteristics by both the selection of its operating spring and the extent to which such spring is compressed by an adjusting ring included in the gas lift valve supporting one end of the operating spring.

It will also be seen that an alternate form of secondary valve of the gas lift valve includes a spacer ring to permit increase in the size of the gas lift valve without a corresponding increase in the effective area of the secondary valve over which the casing and tubing string fluid pressures are applied and then minimizing an increase in the requirements for the secondary valve spring.

It will be further seen that the gas lift valve includes means for reduction of its maximum flow rate through an annular orifice assembly to a level permitting continuous flow through the valve from the casing annulus into the tubing string where the well fluids being lifted are continuously lightened as distinguished from intermittently introducing large slugs of lift gas into well fluids in the tubing string.

The foregoing description of the invention is explanatory only, and changes in the details of the construction illustrated may be made by those skilled in the art, within the scope of the appended claims, without departing from the spirit of the invention.

What is claimed and desired to be secured by Letters Patent is:

1. A gas lift valve for controlling fluid flow between an annular space in a well around a tubing string including such gas lift valve into a central flow passage through said tubing string comprising: mandrel means provided with a longitudinal flow passage extending therethrough; means providing an annular concentric flow passage on said mandrel means and having port means communicating the annular space exteriorly of said valve with said longitudinal flow passage; first valve means supported by said mandrel means communicating with said annular flow passage and responsive to fluid pressure in said annular space exteriorly of said valve for controlling flow through said annular flow passage from said annular space in said well to said longitudinal flow passage; and second annular valve means surrounding said longitudinal flow passage supported by said mandrel means in said annular concentric flow passage between said first valve means and said port means communicating with said longitudinal flow passage in flow related series with said first valve means, said second annular valve means having a first area in fluid communication with the annular space exteriorly of said valve whereby said second annular valve means is biased toward closed position by such fluid pressure exteriorly of said valve, said mandrel means having annular means isolating said first area from said annular concentric flow passage, whereby said first area is exposed to only said pressure exteriorly of said valve; said second annular valve means having a second area in fluid communication with said annular concentric flow passage and said longitudinal passage through said mandrel means whereby said second annular valve means is biased toward open position by the fluid pressure in said flow passage through said mandrel means; and resilient means on said mandrel means biasing said second annular valve means toward open position.

2. A gas lift valve as defined in claim 1 check valve means is disposed in said annular concentric flow passage between said first valve means and said second annular valve means preventing flow in said concentric flow passage from said second valve means to said first valve means.

3. A gas lift valve in accordance with claim 1 including means biasing said first valve means toward closed position, said first valve being biased toward open position by fluid pressure around said gas lift valve independently of the fluid pressure in said flow passage through said mandrel.

4. A gas lift valve for inclusion in a tubing string of a well to control fluid flow into said tubing string from an annular space within said well around said tubing string to lift well fluids within said tubing string above said gas lift valve to the surface, said gas lift valve comprising: a mandrel having a longitudinal bore providing a central flow passage communicating at the upper and the lower ends thereof with said tubing string when connected in said tubing string, said mandrel having port means communicating with said central flow passage; means supported on said mandrel providing an annular concentrically positioned flow passage communicating the exterior of said gas lift valve with said mandrel port means; a first main valve disposed within said concentric flow passage for controlling fluid flow from around said gas lift valve into said concentric flow passage toward said mandrel port means, said main valve comprising a flexible sleeve member communicating on one side with fluid pressure around said gas lift valve; means supported On said mandrel providing a dome chamber communicating with the other side of said first main valve for containing fluid under pressure to bias said first main valve outwardly toward a closed position; a second annular valve supported in said concentric flow passage between said mandrel port means and said first main valve for controlling fluid flow through said concentric flow passage; said second valve comprising a ring member slidably supported around said mandrel within said concentric flow passage for movement between an open first position and a closed second position, and a ring shaped valve seat supported on said mandrel engageable by said second valve ring member at said closed second position for preventing flow through said concentric flow passage; means supported on said mandrel forming an isolated annular pressure responsive surface on said second valve and communicating said surface of said second valve with the outside of said gas lift valve for biasing said second valve toward a closed position responsive to fluid pressure around said gas lift valve; another surface of said second valve being in communication with fluid pressure within said concentric flow passage whereby said second valve is biased toward open position by fluid pressure within said concentric flow passage; and resilient means supported by said mandrel and operatively associated with said second valve for biasing said second valve toward open position.

5. A gas lift valve as defined in claim 4- wherein said mandrel is provided with an external annular orifice-ring supporting flange projecting into said concentric flow passage around said mandrel between said first main valve and said second pilot valve, said flange having at least a portion of the outer boundary thereof spaced from a surface defining the outer Wall of said concentric flow passage whereby fluid may flow through said concentric flow passage past said flange, said flange being provided with means for supporting an orifice ring to reduce fluid flow through said concentric flow passage past said flange.

6. A gas lift valve as defined in claim 5, including an annular orifice ring supported by said orifice ring flange in said concentric flow passage, said orifice ring having at least a portion of the outer surface thereof spaced from said surface defining the outer wall of said concentric flow passage around said mandrel to permit limited fluid flow through said concentric flow passage past said orifice ring.

7. A gas lift valve as defined in claim 6, including a spacer ring fitting in concentric substantially fluid tight relationship around said second valve for partially supporting said second valve from an outside wall portion of said gas lift valve.

8. A gas lift valve as defined in claim- 4, wherein said resilient means is an annular spring, and said second valve is supported by one end of a concentric operator sleeve engaged at the other end thereof with said spring for biasing said pilot valve toward open position, said operator sleeve sliding in concentric relationship over said second valve seat assembly and having longitudinal 15 slots therein permitting fluid communication through said concentric flow passage in said slots past said second valve seat assembly.

-9. A gas lift valve as defined in claim 8, including a concentric flexible check valve supported in said concentric flow passage around said mandrel between said first main valve and said second valve for preventing flow in said concentric flow passage toward said first main valve.

10. A gas lift valve for inclusion in a tubing string in a well to control fluid flow from around said tubing string in said well into said tubing string to aid in lifting well fluids within said tubing string to the surface, said gas lift valve being adapted to open responsive to fluid pressure within said tubing string and to close responsive to fluid pressure within said well around said gas lift valve, said gas lift valve comprising: a tubular mandrel having a longitudinal bore therethrough defining a central flow passage through said mandrel communicating at opposite ends thereof with said tubing string when said gas lift valve is secured in said tubing string; an upper sleeve supported in concentric spaced relation around said mandrel; an annular head member secured on said mandrel supporting the upper end of said upper sleeve; an annular base member disposed around said mandrel supporting the lower end of said upper sleeve; the outer surface of said mandrel within said upper sleeve and the inner surface of said upper sleeve defining a dome gas chamber extending between said head and base members for containing a fluid under pressure; means providing a port communicating with said dome gas chamber for charging said chamber with fluid under pressure; means for closing said port to seal said fluid within said dome gas chamber; an intermediate sleeve disposed in concentric spaced relation around said mandrel, the upper end of said sleeve being supported from said annular base member at the lower end of said upper sleeve and the lower end of said intermediate sleeve being supported from an annular ring support member on said mandrel spaced below said base member; a lower sleeve supported in concentric spaced relation around said mandrel, the upper end of said lower sleeve being supported by said annular ring support member; ring retainer means secured on said mandrel for supporting the lower end of said lower sleeve; said mandrel and said intermediate and lower sleeves in combination defining an annular longitudinal flow passage around said mandrel within said sleeves; said intermediate sleeve having port means communicating said annular flow passage with the outside of said lower sleeve means; said mandrel having port means longitudinally spaced from said port means in said intermediate sleeve communicating said bore of said mandrel with said annular flow passage whereby said port means in said intermediate sleeve, said annular flow passage, and said port means in said mandrel define an exclusive flow path for fluids between said bore of said mandrel and the outside of said gas lift valve; a flexible main valve sleeve secured in concentric relationship between said mandrel and said intermediate sleeve means along said ports in said intermediate sleeve for covering said port to prevent flow through said ports between said concentric annular flow passage and the outside of said gas lift valve; the interior of said main valve sleeve defining an annular chamber communicating with said dome gas chamber whereby fluid under pressure in said dome gas chamber is transmitted into said main valve sleeve for biasing said valve sleeve radially outwardly within said intermediate sleeve for covering said ports in said sleeve to prevent fluid communication through said ports into said annular flow passage; a second annular valve disposed in said annular flow passage longitudinally spaced between said main valve and said port means in said mandrel for controlling fluid flow through said annular flow passage, said second valve having a first annular surface portion isolated by means associated with said mandrel so as to be exposed to fluid pressure outside of said gas lift valve for biasing said second valve toward closed position and a second annular surface portion sealed from said first annular surface portion and exposed to fluid pressure within said annular flow passage for biasing said second valve toward open position; spring means operably connected with said second valve biasing said valve toward open position; and annular flexible check valve means disposed within said annular flow passage between said main valve and said first valve and said second valve to prevent fluid flow through said annular flow passage toward said first valve.

11. A gas lift va'lve as defined in claim 10, wherein said second valve comprises an annular valve seat assembly supported around said mandrel, a longitudinally slidable annular valve member movable in said annular flow passage between open and closed positions relative to said seat assembly, said first surface portions of said valve member being in fluid communication through port means in said lower sleeve with the outside of said lower sleeve for biasing said valve member toward said seat assembly responsive to fluid pressure around said gas lift valve, and said second surface portions of said valve member being exposed to fluid pressure within said annular flow passage biasing said valve member toward open position away from said annular valve seat, and a longitudinally slotted operator sleeve supported over said annular seat assembly between said valve member and said spring means permitting fluid flow within said anular flow passage along said operator sleeve past said seat assembly while transmitting force between said valve member and said spring means.

12. A gas lift valve as defined in claim '10, wherein said second valve includes: an annular valve seat assembly disposed around said mandrel and having crimped portions received in an external annular recess of said mandrel for holding said seat assembly against longitudinal movement on said mandrel; said lower sleeve includes a support ring having a tubular portion disposed in concentric spaced relation between said mandrel and said lower sleeve defining an annular space communicating at one end with the outside of said lower sleeve through port means provided therein and at the other end with said annular flow passage; an annular valve member having a tubular portion slidable in said annular space; seal means supported in substantially fluid tight relationship with said tubular portion of said valve member for sealing first and second surface portions of said valve member from each other, said first surface portions of said valve member being exposed to fluid pressure within said annular space transmitted through said port means in said support ring from outside of said gas lift valve and said second surface portions of said valve member being exposed to fluid pressure transmitted through said annular flow passage; and an operator sleeve disposed within said annular flow passage between said valve member and said spring means operatively interconnecting said valve member and said spring means, said operator sleeve having longitudinal slots permitting fluid flow along said annular flow passage around said annular seat assembly.

13. A gas lift valve as defined in claim 10, wherein said mandrel is provided with an external flange projecting into said annular flow passage and provided with means for supporting an orifice ring and having irregular peripheral surface portions spaced from surface portions defining the outer wall of said annular flow passage to permit fluid flow within said annular flow passage past said flange on said mandrel.

14. A gas lift valve as defined in claim 13, including an orifice ring supported on said flange on said mandrel for the limiting fluid flow space around said flange within said annular flow passage.

15. A gas lift valve as defined in claim 11, including I 7 18 an annular spacer ring around said valve member of said References Cited second valve and annular seal means between said spacer UNITED STATES PATENTS ring and said valve member, said spacer ring minimiz- 3,223 109 12/1965 Cummings ing the surface portions of said valve member exposed to fluid pressure Within said annular flow passage and 5 ALAN COHAN, Primary Examiner. around said gas lift valve exterior of said lower sleeve s L means. I 103232 

